There were many pests to see at the Cornell University Research
Farm in Valatie this week including alfalfa weevil, clover-root
curculio adults on alfalfa and Stagonospora nodorum blotch on triticale.
Oh yes, a few weeds emerging too.

Clover-root curculio
adult weevils can often be found cruising alfalfa this time
of year. Adults nip at leaves and their below the ground feeding
grub-like larvae feed on root nodules and damage alfalfa roots,
which can predispose plants to infection by root diseases.

Unfortunately, there is not much we can currently do to manage
this insect with the expectation of rotating a different crop. This
pest builds in population in a field over time. These small weevils
are 1/8 inch long and 1/16 inch wide with short, broad snouts. The
adult weevil is brownish-black and covered with grayish hair and
scales. Adult curculios chew the margins of leaves leaving C shaped
notches. Clover-root curculio larvae feed below-ground on nodules,
small rootlets, and chew out portions of the main root. As a result
of larval feeding on roots, diseases such as fusarium crown and
root rot can enter the plant. Clover-root curculio will feed on
several types of clover and alfalfa.

I discovered Stagonospora nodorum blotch on the lower leaves
of triticale in Tom Kilcerís research plots. Splashing rain or thunderstorms
can move spores from field surface on to the plant. This fungal
pathogen may also reside in residue on the field surface. In wheat,
greatest yield losses occur when the flag leaf and the next two
lower leaves become infected by the time the wheat flowers in late
May. Leaf lesions begin as very dark brown flecks or spots, sometimes
with a yellow halo. These small irregular lesions expand into oval
light brown lesions with dark brown centers. As lesions enlarge,
they become dark brown and the centers turn grayish-white in color
as tiny brown or black dots (pycnidia) develop within them.

With the warm, dry conditions last week, then the weekend rain
storms, winter wheat stands are vigorously growing. But with our
cool late April weather, this is the prime time to monitor fields
for wheat spindle streak mosaic virus and yellow dwarf.

Wheat spindle streak mosaic virus (WSSMV) symptoms are yellow-green
dashes or streaks with tapered ends, running parallel to the leaf
veins. A soilborne fungus that attacks the roots of wheat in the
fall transmits WSSMV. Symptoms often show up on plants in wet soils,
but excessive moisture in the spring is not required for infection
to occur. Cool spring temperatures like we are now experiencing
are ideal for continued development of WSSMV. As temperatures warm,
plants usually outgrow the disease.
Click here to see photos of WSSMV

Yellow dwarf symptoms include yellowing of leaf tips, sometimes
progressing to red or purple colors. Several species of aphids common
in New York transmit yellow dwarf. If winter wheat was planted too
early in the fall, aphids may have had time to infest and infect
plants. If yellow dwarf infections occur in the spring, instead,
symptoms will appear later. Stay tuned to the Pest Report for updates.
Photos of symptoms can be seen atYellow
dwarf affecting a whole field and
Yellow dwarf: healthy vs. diseased plant

Rescue treatment options to eliminate infections from viral disease
are not available. Fortunately, severe outbreaks of viral diseases
are uncommon in wheat in NY since resistance is present in most
of the commonly grown cultivars. However, scouting now for these
diseases, and submitting suspicious samples for correct identification
to the Cornell Plant Disease Diagnostic Clinic (http://plantclinic.cornell.edu/)
has the value of verifying the presence of these diseases. Next
time wheat is planted in the same field, preventative management,
such as planting a resistant cultivar, becomes an easy choice.

This week I discovered a few adults, eggs and 1st instar alfalfa
weevil larvae at the Cornell University Research Farm in Valatie.
There was only about 5% tip feeding in each field. Newly hatched
larvae are about 1/16 inches long and yellow to light green in color.
As larvae feed, grow and molt they become green with white stripes
down their back. Larvae have a dark brown head. Larvae ultimately
grow to reach 3/8 inches long before pupation about early June in
New York. Recall that these larger larvae have big appetites and
are responsible for 80% of the alfalfa lost to weevil feeding. Check
out these websites for correct identification:
Alfalfa Weevil Eggs and
Alfalfa Weevil Larvae. Check out our on-line publication,
IPM for Alfalfa Weevil.

Winter annual weeds are popping up in wheat fields and reduced-tillage
fields all across our area. Among the most commonly observed so
far this spring are henbit, purple deadnettle, common chickweed,
and corn chamomile. The wild mustards (including yellow rocket,
shepherdís purse, and wild radish) are also present, but they are
still in their rosette stages and thus are not yet catching our
attention. Stay tuned to the pest report next week for more information.
Winter annuals germinate in the fall, overwinter as seedlings, and
flower and go to seed in the spring.

Letís highlight a couple winter annuals to watch for while scouting:

Corn Chamomile plants are mostly still in the rosette stage.
The rosettes are small and low to the ground, with finely divided
foliage. The small daisy-like flowers may be seen starting in mid-May.
Click here for a photo
of corn chamomile

Henbit: The small tubular pink to purple flowers are seen in
the upper whorls of leaves. Stems are square, as is typical of the
mint family. Lower leaves are heart-shaped, while the upper leaves
are deeply lobed.

Purple deadnettle is flowering like crazy after the warm weather
last week. This weed also has a square stem and small tubular flowers
that appear in the upper whorls of leaves. Leaves are triangular
in shape and less deeply lobed than henbit. The upper leaves of
purple deadnettle are purple, and the flowers are pale purple. Photos
to help you distinguish henbit from purple deadnettle can be seen
on this web page from Michigan State University:
Henbit
vs. Purple Deadnettle

Winter annuals present the most significant pest problem in winter
wheat, where the life cycle of the weed matches the life cycle of
the crop. Wheat is now actively growing, and the winter annual weeds
are competing for nutrients and moisture. If scouting indicates
that herbicides are necessary, applications should be made no later
than the fully tillered stage of wheat development. More information
on weed management options in wheat can be found in the small grains
section of the online version of The 2006 Cornell Guide for Integrated
Field Crop Management:
http://ipmguidelines.org/fieldcrops/5-SmallGrainCrops/5.09Weeds.htm

Warmer spring temperatures signal alfalfa snout beetle (ASB)
adults to begin their emergence from the fields where they have
been feeding as larvae on alfalfa roots for the past two years.
Last week Dr. Elson Shields and his entomology crew sounded the
call to view alfalfa snout beetles in their annual migration.

Alfalfa snout beetles (ASB) are root-feeding weevils found only
in northern New York State along Lake Ontario and the St. Lawrence
seaway (from Cayuga to Clinton counties), southern Ontario's Wolfe
Island, Grenville and Leeds counties, and in central Europe.

Alfalfa snout beetles (ASB) typically emerge a few weeks before
of our other alfalfa munching beetle, the alfalfa weevil, and are
more than twice their size. ASB's are mottled gray, humpbacked,
1/2 inch long, do not fly, and are all females. Adult alfalfa snout
beetles leave alfalfa fields this time of year in mass (by the tens
of thousands) in search of new alfalfa fields to lay their eggs.
Once they find a suitable location ASBís feed on new alfalfa shoots
and lay eggs that hatch into the voracious root feeding larvae.
While adult feeding can trim the tops of alfalfa and other hosts,
itís larval feeding, associated root damage, the potential for disease
infection and overwintering injury that contribute to the real coup
de grace and stand loss. Alfalfa snout beetle larvae are legless,
white, 1/2 inch long, and can be found feeding on alfalfa roots
within a foot of the soil surface in mid to late summer. Larvae
feed on side roots, and girdle the main taproot causing death to
the plant. In early fall the larvae move deeper in the soil where
they spend the winter. The following spring the larvae move 10-12
inches from the surface, pupate by mid-summer and become inactive
adults, which remain in the soil until the following spring. ASB
damage in the spring looks similar to winter killed alfalfa with
plants failing to "green up".

Alfalfa Snout Beetles in your neighborhood? In addition to alfalfa,
other host plants for ASB include: red clover, dock, wild carrot,
quackgrass, and white clover. ASB control is best achieved with
a three year rotation of alfalfa with a row crop. Nonhosts, i.e.
good crops to have in rotation to minimize ASB losses include: corn,
wheat, oats, soybeans, potatoes, and birdsfoot trefoil. Insecticides
are not recommended to control ASB.

Future control options? Cornell researchers are currently looking
into two possible avenues of future ASB management: resistant alfalfa
varieties (Don Viands and Cornell's Plant Breeding Forage Group)
and biological control using entomopathogenic nematodes (Elson Shields
and Graduate Students in Cornell's Entomology Department). Wish
them luck!

Alfalfa snout beetles feeding on bedstraw plants near the edge
of an alfalfa field in Jefferson county.

The USDA Cereal Rust Bulletin (April 18) reports that wheat leaf
rust is prevalent throughout the southern U.S. this spring. Colleagues
in Ontario and Pennsylvania have also found locally over-wintered
leaf rust. So it would not be surprising if we also find some pockets
of over-wintered rust in New York, especially areas that had some
snow cover this winter. In the past I have found the large aerial
rust showers from the southern areas (often arrive with thunderstorms
in June) to dwarf the role of any over-wintered, local inoculum,
but it would be good to keep an eye on this.

Wheat stripe rust is at low levels so far in the south, especially
in the Mississippi Delta states.

Oat crown rust is at low levels in the south. The alternate host
buckthorn is breaking bud now in NYS. Watch for the yellow-orange
aeciospore stage on developing buckthorn leaves over the next few
weeks - aeciospores will infect nearby oat crops.

Scouting for soybean rust continues on kudzu patches from Florida
northward to southern Illinois, and westward to Texas. Many of the
soybean sentinel plots have been planted in most southern and some
mid-western states. Soybeans in sentinel plots have emerged as far
north as central Illinois. Currently, there are no reports of rust
on newly planted soybean in 2006 including volunteer plants. Rust
has been confirmed in five counties in Alabama, 11 in Florida, four
in Georgia, and one in Texas. No new positive counties have been
reported since the first week of March. The south has been dry with
some recent rains reported in the southeast including Florida to
the north and east. The southwest continues to be dry. View state
commentaries for detailed reports of planting and scouting information.